Mysterious migraines after heart surgery may finally be explained
After common heart surgery, some patients experience migraines with visual auras – temporary vision disorders, such as flashing lights and zigzag lines. The reason for this unusual complication was a mystery, but now research suggests that blood clots in the brain can be the culprit.
“These [clots] We did not first think of symptoms or clear consequences clear “, co-author of the study Dr Gregory MarcusA cardiologist at the University of California in San Francisco, told Live Science in an email.
The new study, published on July 7 in the journal Heart rhythmoffers a new theory on the reasons why these mysterious migraines are manifested.
A sign of something serious?
To treat irregular arrhythmias or cardiac beats, doctors make a catheter removal, which involves inserting a tube into the heart to burn or scars of any heart tissue causing irregularity. About 360,000 people in the United States Follow surgery every year.
Different catheter ablation techniques can be used according to the location of the defective heart fabric. A strategy, called “transseptal puncture“Creates an opening between two heart chambers, while another, known as”retrograde approach“Do not require this hole.
But in the months that followed a catheter removal, 2.3% of patients without history of Migraines with visual auras Report these symptoms for the first time. The auras themselves generally appear just before or during a migraine attack.
These new symptoms are worrying because the ischemic stroke, which occurs when the blood flow to the brain is blocked, is 2.6 times more likely In people under the age of 45 who experience migraines with visual auras, and it is 3.7 times more likely in women in the same age group that live them. Thus, these migraines could be prescribe of serious cardiovascular events.
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Mysterious origin of the visual auras
Scientists have several theories to explain why the ablation of the catheter could be linked to migraine. A theory postulates that the hole created by the transseptal puncture could trigger the complication by relaxing the blood from its typical path.
Blood circulates normally from the right side of the heart to the lungs, then on the left side of the heart, and finally to the rest of the body, including the brain. However, a puncture could allow blood to travel directly From left to right heart roomsbypassing the lungs. Researchers think that this detour could allow a certain type of neurotoxin – normally decomposed by pulmonary enzymes – to reach the brain and to trigger auras.
However, MRI analyzes have revealed another visual-aua trigger: brain lesions caused by embolism, meaning bits of blood clotsAir bubbles or fatty deposits crossing blood circulation and then obstructing blood vessels in the brain.
Migraines with visual auras also occur in people with no history of cardiac surgery, but the mechanism behind the phenomenon is not clear in these scenarios. Marcus said that previous studies have shown that people who experience these auras, in general, also tend to have a history of brain embolism.
“But it was very difficult to determine if there was a causal relationship between the two,” he said. Since brain embolism tends to be ephemeral, clinicians should carry out analyzes at the same time as the patient reports the Auras to identify a link, he said.
Patients undergoing the ablation of the catheter may have a chance to explore the connection, as surgeries can reveal more embolism. Debris of burnt cardiac fabric can move to the brain, block blood flow and therefore starve the brain tissue of oxygen and nutrients, Marcus said. These lesions are temporary, but he and his team suspected that the embolique can be linked to the Auras after cardiac surgery.
They therefore conducted a test in which 63 patients with arrhythmia were treated with transseptal puncture and 57 with the retrograde approach. Patients underwent brain MRI the next day and fulfilled a questionnaire a month later to report all visual. It turned out that the two surgical techniques were also likely to result in visual auras.
“Our results here show that the presence of a hole which provides communication between the right and left sides of the heart is not at all necessary for these visual auras to occur,” said Marcus. However, looking at MRI analyzes, they found that patients with brain embolis after surgery had a chance 12 times higher to develop visual auras than patients without embolism.
Following steps
Once considered no symptoms, brain embolism can at least contribute in part to visual auras, said Marcus, adding that scientists should explore if embolisms are also linked to more serious problems, such as a stroke.
The new study, however, has some weaknesses. Dr Andrew LeeAn ophthalmologist at the Houston Methodist Hospital in Texas which was not involved in the work, noted that “the main limits were that the symptoms of migraine were self -depressed”. It is possible that “even a validated and prospectively obtained questionnaire can classify the symptoms of a given participant,” Lee at Live Science told an email.
He also noted that the study had not assessed if patients had a natural hole in their hearts, called oval patented foramen. This hole between the heart rooms is formed during development and closes shortly after birth in most people, but in 25% of people, It remains open. The hole was linked to migraines, visual auras and blows When present in adults.
Since the new study only explored if brain damage was linked to visual auras immediately after heart surgery, “future work is necessary to determine whether the results of this study can be generalized to migraine in general,” said Lee.
Publisher’s note: Dr Gregory Marcus consults and has equity in Incarda, a drug delivery company aimed at treating cardiovascular disease, including arrhythmia.
This article is for information only and is not supposed to offer medical advice.
